he says he'll kill himself

I really do love my boyfriend but our families don't get along and I really hate his because they disrespected my mom and my son. I do feel like he's cheating just because of what his mom and sister have told me but I am still with him because I cannot prove or have not seen him cheat. But, he acts like I have to stay with him. I do want to be with him but he mentioned some times during arguments or just expressing his feelings that he will kill himself if I leave and I'm confused on whether I want to be with him or not but I feel like I have to stay because I already lost someone from suicide in January and I'm just terrified. I need as much advice as I can get it please from anyone of you.